Reducing Alcohol Consumption Among Risky Drinkers in the General Population of Sweden Using an Interactive Mobile Health Intervention: Protocol for a Randomized Controlled Trial

Background Harmful use of alcohol continues to be a leading contributor to premature deaths globally. Not only does harmful drinking have consequences for the individuals consuming at increased levels, but it may also result in a range of negative consequences for their family members and friends. Interventions delivered via mobile phones (mobile health [mHealth] interventions) could potentially support risky drinkers seeking help to reduce their alcohol consumption. Objective This protocol describes a randomized controlled trial that aims to validly estimate the effect of a novel mHealth intervention targeting risky drinkers in the general population of Sweden. Nested within the trial are 3 substudies that focus on methodological and user satisfaction research questions. Methods A 2-arm parallel group randomized controlled trial will be employed to estimate the effect of the novel intervention. Participants will be recruited through Web advertisements and social media. The inclusion criteria are as follows: 18 years or older, ownership of a mobile phone, and being classified as a risky drinker according to Swedish guidelines. Participants allocated to the intervention group will receive a novel mHealth intervention. The intervention consists of weekly screening, personalized feedback on current consumption, functions allowing for planning of future consumption, as well as a series of messages delivered throughout the week. Participants allocated to the control group will receive a short message regarding negative consequences of alcohol consumption and a hyperlink that offers more information. Following 2 and 4 months after randomization, both groups will be asked to complete follow-up questionnaires (2-month interval being primary). Primary outcomes are weekly alcohol consumption and heavy episodic drinking. Participants in the control group will be given access to the novel intervention after completing the 4-month follow-up. The trial includes 3 substudies: We will explore whether the mode of presenting information before participants giving informed consent affects participation rates and recall of trial parameters, investigate if the content of the short message received by the control group affects study outcomes and requests for more information, and explore user satisfaction with the intervention and reactions of the control group. Results Participant recruitment is planned to begin in April 2019 and to last for a maximum of 24 months. The first dataset will be available approximately 2 months after the final participant has been recruited, and the final dataset will be available approximately 2 months later. No participants had been recruited at the time of submitting this protocol. Conclusions If found effective, the intervention has the potential to reduce negative consequences of alcohol consumption for individuals. The technology has been designed to have potential for extensive reach among those who may benefit. Trial Registration ISRCTN Registry ISRCTN48317451; http://www.isrctn.com/ISRCTN48317451 (Archived by WebCite at http://www.webcitation.org/779tKLsu3) International Registered Report Identifier (IRRID) PRR1-10.2196/13119

6. How confident are you that you will be able to reduce your alcohol consumption? (10-point scale ranging from 1 = "Not at all" to 10 = "Very confident") 7. How important is it for you to reduce your alcohol consumption? (10-point scale ranging from 1 = "Not important" to 10 = "Very important") 8. How well do you know how to reduce your alcohol consumption? (10-point scale ranging from 1 = "Not well at all" to 10 = "Very well") Note: Participants are reminded of the definition of a standard unit by graphical means.

MEDIATION QUESTIONNAIRE (ONE-MONTH FOLLOW -UP)
1. How confident are you that you will be able to reduce your alcohol consumption? (10-point scale ranging from 1 = "Not at all" to 10 = "Very confident") 2. How important is it for you to reduce your alcohol consumption? (10-point scale ranging from 1 = "Not important" to 10 = "Very important") 3. How well do you know how to reduce your alcohol consumption? (10-point scale ranging from 1 = "Not well at all" to 10 = "Very well") 1. How often, during the past month, have you consumed four/five (female/male) or more standard units on one occasion? (numerical measure) 2. How many standard units of alcohol did you consume last week? (numerical measure) 3. How confident are you that you will be able to reduce or keep a lower level of alcohol consumption? (10-point scale ranging from 1 = "Not at all" to 10 = "Very confident") 4. How important is it for you to reduce or keep a lower level of alcohol consumption? (10-point scale ranging from 1 = "Not important" to 10 = "Very important") 5. How well do you know how to reduce your alcohol consumption? (10-point scale ranging from 1 = "Not well at all" to 10 = "Very well") Note: Participants are reminded of the definition of a standard unit by graphical means.

RECALL OF TRIAL PROCEDURE (TW O-MONTH FOLLOW -UP)
Before you accepted to join this trial you were given information about the trial procedure. We would like to ask you a few questions about this information.
1. Which one of these statements most accurately describes your recall of group allocation: • I recall reading information about two groups, but no details.
• I recall reading information about two groups, and that each group was going to be given access to either information or immediate access to a new mobile phone support tool.
• I do not recall reading about allocation to two groups.
2. (If second option is picked to question 1): Which one of the groups were you allocated to?
• I was given immediate access to information.
• I was given immediate access to a new mobile phone support tool.
• I do not know.
3. With respect to how personal data would be handled during the trial, which of these do you recall reading about? You can select multiple options, and if you cannot recall any then select "I do not recall reading about personal data": I recall reading about: • How data would be stored in connection to my phone number • How my phone number would be encrypted when stored • My rights to the data according to GDPR • Who to contact in case I have a complaint regarding data handling • How phone numbers were going to be treated once the project is complete • That my data cannot be traced to my phone number after the project is complete • I do not recall reading about personal data 4. Which one of these statements most accurately describes your recall of how data collected from this trial would be analysed and the results be made available?
• I recall reading about data analysis and communication of results, but no details.
• I recall reading about data analysis and communication of results, and some details of the analysis part.
• I recall reading about data analysis and communication of results, and some details of the communication part.
• I recall reading about data analysis and communication of results, and some details of both parts.
• I do not recall reading about data analysis nor communication of results.
Note: Each question will also have a free-text area in which participants can leave further comments and impressions.

INTERVENTION GROUP EXPERIENCE (FOUR-MONTH FOLLOW -UP) SYSTEM USABILITY SCALE
Each item below is scored by respondents on a scale from 1 = "Strongly agree" to 5 = "Strongly disagree" [57].
• I think that I would like to use this system frequently.
• I found the system unnecessarily complex.
• I thought the system was easy to use.
• I think that I would need the support of a technical person to be able to use this system.
• I found the various functions in this system were well integrated.
• I though there were too much inconsistency in this system.
• I would imagine that most people would learn to use this system very quickly.
• I found the system very cumbersome to use.
• I felt very confident using the system.
• I needed to learn a lot of things before I could get going with the system.

EXPERIENCE OF SUPPOR T PROVIDED
• Overall, how well suited do you believe that the support was to your needs? (1 = "Not very well" to 5 = "Very well"). Please leave a comment describing your needs and how the intervention matched or did not match them (Free-text).
• Do you believe that the content in the dashboard would be helpful for people that want to reduce their consumption? (1 = "Not very helpful" to 5 = "Very helpful") • Do you believe that the content in the SMS messages would be helpful for people that want to reduce their consumption? (1 = "Not very helpful" to 5 = "Very helpful") • If you were to continue using the support, for how much longer would you want to use it? Questions asked to the control group at the end of the trial (four-month follow-up) prior to giving them access to the intervention.
You were part of the group that was given access to information before being given access to the mobile phone based support. Out of the options listed below, which best describes your immediate reaction and your later actions. Please also leave a comment to explain your response. o I found other support that I used to reduce my consumption (please leave a comment on which support you used).
o I gave up on the idea of reducing my alcohol consumption.
• Did you look at the information given and did you find it useful?
o I looked at the information and found it useful to think about my drinking.
o I looked at the information and found that it was not useful. o I did not look at the information.
o I do not know.